Conical disc for centrifuges and the like



April 2, 1957 H. w. THYLEFQRS I 2,787,413

CONICAL DISC FOR CENTRIFUGES AND THE LIKE Filed Oct. 4, 1955 IN VEN TOR.

ATTOR N Ys hire States Patent CONICAL DISC FOR CENTRIFUGES AND THE LIKE Heuric Wilhelm Thylefors, Stockholm, Sweden, assignor to Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Application Qctober 4, 1955, Serial No. 538,477

Claims priority, application Sweden October 11, 1%4

2 Claims. (Cl. 233-41) This invention relates to conical or frusto-conical discs used in centrifugal separators and similar apparatus, and has particular reference to an improved disc of the type having a stilfening edge forming the outer periphery of the disc and provided with a guide slot.

Centrifugal separators are commonly provided with a series of generally conical discs located in the separating chamber of the centrifugal bowl and spaced from each other to form thin spaces between the discs, where the centrifugal separation takes place. It is also common practice to provide the outer peripheries of the discs with guide slots adapted to mate with a rib or other part fixed to the inner wall of the bowl, whereby the discs are located in predetermined angular positions relative to each other and to the bowl, as is well known to those skilled in the art. These guide slots have in some instances been stamped out of the peripherally extending stiitening edges of the discs. This has weakened the stiffening edge and it has therefore been necessary to provide it with a reinforcement in the form of a so-called guide caulk. This caulk, the outer contour of which follows the contour of the stiffening edge with the guide slot arranged therein, has usually been fixed in place by spot-welding. in spite of the caulk, however, the edge of the disc is substantially weakened at the region of the guide slot. When handling the discs, particularly when they are washed, they are squeezed into oval form, the deformations becoming greatest, of course, at the region of the guide slot. At this region, the smooth curve of the disc edge is interrupted or broken. After some time, the discs begin to crack, starting from the inner corners of the slot, and the crack then spreads rapidly toward the center of the disc, which must then be discarded.

in other prior discs, the guide slot has not been formed in the stiifening edge proper but a guide caulk has been placed on this edge, the caulk projecting beyond the periphery of the stifiening edge and the guide slot being formed in this projecting portion of the caulk. In this as well as in the aforementioned design, the maximum thickness of the guide caulk is limited by the spacing between the stiflening edges of the discs and cannot, therefore, exceed this spacing. On the other hand, it is desirable to provide the maximum number of discs within the separating chamber of the centrifuge in order to increase the separating efficiency, and this means a minimum thickness of the interspaces between the discs, if the disc thickness is unchanged. The tendency in modern designs is to make the disc interspaces smaller than the disc thickness. Therefore, the maximum possible thickness of the guide caulks is reduced so that it becomes smaller than the thickness of the stiffening edge. This fact, which also increases the difiiculties in the design first described, means that the projections on each side of the guide slot are weaker than if the guide slot had been formed directly in the stiffening edge, which normally is about 40% thicker than the disc proper. The projections therefore are liable to deformation during the handling of the discs.

The above-mentioned difficulties are eliminated by the present invention. According to the invention, the contour of the stiffening edge of the disc in the vicinity of the guide slot is bulged outward in relation to the otherwise circular periphery of the disc edge, and the guide slot is formed by cutting into the bulged part of the stifiening edge. The guide slot preferably extends radially inward no farther than to the circle formed by the rest of the periphery of the disc, so that the width of the stiffening edge will not be smaller at the region of the guide slot than along the other parts of the edge. In this way, the strength of the stifiening edge remains unreduced in the vicinity of the guide slot. Finally, by making fillets of relatively great radii at the inner corners of the slot, the strain concentrations there are minimized. if a disc constructed in this way is squeezed oval, the deformation will be evenly distributed along the entire stifiening edge and will not be concentrated at the guide slot area. The increase of the stresses normally resulting from the deformation is retarded due to the great corner radii of the slot. The result is that the disc no longer cracks starting at the guide slot.

The accompanying drawing shows by way of example a bowl disc intended for use in a centrifugal separator for rubber latex, the guide slot being located at the outer periphery of the disc. In the drawing, Fig. l is a plan view of a sector of a conical bowl disc; and Fig. 2 is a sectional view of'the outer part of the disc, taken along line llII in Fig. 1.

Referring to the drawing, the numeral 1 designates the usual frusto-conical portion of the disc, and 2 designates the horizontal stifiening edge forming the outer periphery of the disc. The broken line 3 designates the arc of a circle centered on the disc axis (not shown) and having a radius equal to that of the periphery of the stiffening edge 2 at its main portion. The bulged part of the stiffening edge, in which the guide slot 4 is provided, is shown at 5. It will be observed that the slot 4 extends radially inward only as far as the circle 3, so that the stiffening edge 2 is not weakened by this slot.

I claim:

1. A disc for centrifugal separators, and the like, which comprises a generally conical part, a stiffening edge extending along the periphery of the generally conical part, and a bulged part extending outward from. the otherwise circular periphery of the stiffening edge, there being a guide slot in said bulged part of the stiflening edge.

2. A disc according to claim 1, in which the slot extends radially inwand no farther than to the radius of said otherwise circular periphery of the stiffening edge.

Ljungstrom Aug. 15, 1905 Leitch Nov. 16, 1915 

